1. Field of the Invention
The present invention relates to an image scanner applied to image inputting in computers, facsimiles, wordprocessors, etc. and to an illuminating apparatus used for the image scanner.
2. Description of the Related Art
In a conventional image scanner, an original image is read by a semiconductor integrated circuit having multiple photoelectric conversion elements disposed in one array. The reading of the original image by such an image scanner is conducted in such a manner that the scanning of the original image by the photoelectric conversion elements in an array direction of the photoelectric conversion elements is sequentially repeated by moving the original in relation to the semiconductor integrated circuit or vice versa.
In the conventional image scanners, the array direction of the photoelectric conversion elements, which is a main-scanning direction, and the moving direction of the original in relation to the semiconductor integrated circuit or vice versa, which is a sub-scanning direction, are set to be perpendicular to each other.
In the case where the main- and the sub-scanning direction are perpendicular to each other, the image information read by the image scanner is distorted.
When the original image is scanned by the photoelectric conversion elements while continuously moving the semiconductor integrated circuit in relation to the original, a predetermined time is required to sequentially scan the original by each of photoelectric conversion elements from one end to the other end of the array.
Consequently, as compared with the image information by the photoelectric conversion element at the beginning end of the array, the image information by the photoelectric conversion element at the other end of the array is deviated to the upper stream side of the sub-scanning direction, that is the upper stream side of the moving direction of the semiconductor integrated circuit in relation to the original.
As a result, the distortion of the read image is caused and the quality of the read image is lowered.
Additionally, in the conventional image scanners, the semiconductor integrated circuit is provided with only one array of photoelectric conversion elements and between the adjacent photoelectric conversion elements exists a space almost equal to the width of one photoelectric conversion element. As a result, the resolution of the read image information is low.
The inventors and others of the present invention have proposed an image scanner of a long-shaped and fitting type wherein one array of a plurality of lenses and one array of a plurality of semiconductor integrated circuits are arranged to be in parallel to each other and to correspond to each other. In such constitution, the respective lenses should be very precisely arranged so as to correspond to the respective semiconductor integrated circuits. However, in the case where the precise arrangement can not be realized because of manufacturing errors, the image scanners have a few problems, namely, deviation of read pixels at seams of respective reading systems and blurring of image due to loosening of an origin.
Additionally, the entire surfaces of the semiconductor integrated circuit possessing multiple photoelectric conversion elements are usually coated with a resin in order to protect the photoelectric conversion elements and wire bondings. However, the applied resin coating forms a convex. As a result, if light enters the photoelectric conversion elements through the convex resin, convex effect and light scattering occur, which make highly precise reading impossible. The image scanners having such problems are not suited to bar code readers or the like which are required to have a high precision in length measurement.
Further, in the above-mentioned image scanners, a plurality of LEDs as a light source, each of which has almost the same light quantity, are arranged at regular intervals. Although the light source has almost uniform light quantity in linear illuminating, the light quantity decreases in the periphery of the lens when passing through the lens (hereinafter the phenomenon is described as "peripheral dimming").
Further, the above-mentioned long-shaped and fitting type image scanners have a problem that the parts cost is increased because of the necessity of the plurality of semiconductor integrated circuits.
Further, in a conventional illuminating apparatus for illuminating an original provided in the image scanners, for example, the light emitted in parallel to the original to be illuminated from LEDs provided in the illuminating apparatus hardly reaches the original. Thus a sufficient quantity of light for illuminating the original can not be obtained for the number of LEDs.